Re: [PATCH] ALSA: pcm: Fix potential Spectre v1 vulnerability

From: Takashi Iwai
Date: Thu Dec 13 2018 - 03:15:39 EST

On Wed, 12 Dec 2018 22:36:28 +0100,
Gustavo A. R. Silva wrote:
> stream is indirectly controlled by user-space, hence leading to
> a potential exploitation of the Spectre variant 1 vulnerability.
> This issue was detected with the help of Smatch:
> sound/core/pcm.c:140 snd_pcm_control_ioctl() warn: potential spectre issue 'pcm->streams' [r] (local cap)
> Fix this by sanitizing stream before using it to index pcm->streams
> Notice that given that speculation windows are large, the policy is
> to kill the speculation on the first load and not worry if it can be
> completed with a dependent load/store [1].
> [1]
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

Applied now (again after moving the include line into a more
appropriate place).